Many medical patients require precise intravenous delivery of a fluid in desired rates such as either continuous delivery or delivery having a particular flow rate profile. Continuous delivery may be accomplished using gravity or pumps. Conventional medical pumps can also provide controlled drug infusion wherein a drug may be administered at a more precise rate than gravity administration that maintains the drug concentration within a therapeutic margin and out of an unnecessary or possibly toxic range.
Medical pumps may facilitate administration of intravenous therapy to patients both in and outside of a clinical setting. Outside a clinical setting, doctors have found that in many instances patients can return to substantially normal lives, provided that they receive periodic or continuous intravenous administration of medication through the use of ambulatory pumps. Among the types of therapies requiring this kind of administration are antibiotic therapy, chemotherapy, pain control therapy, nutritional therapy, and several other types known by those skilled in the art. In many cases, patients receive multiple daily therapies.
Certain medical conditions require low rate infusions of drugs in solution over relatively long periods, such as from two hours to multiple days. These conditions and others have combined to promote the development of increasingly lightweight, portable or ambulatory infusion pumps that can be worn by a patient and are capable of administering a continuous supply of medication at a desired rate, or provide several doses of medication at scheduled intervals.
A medical fluid infusion system of the types described above typically provides a fluid flow path (or tubing line) between a medical fluid source and a patient. A flow restrictor may be employed along the length of such flow path to limit or control fluid flow to the patient in accordance with a desired fluid therapy or protocol. These systems usually are supplied in a sterile, non-filled condition and the pharmacist or other healthcare provider then compounds or injects the desired medication into the medical fluid source. Sterility of the flow path is maintained until use typically by the use of a luer cap. Prior to connection of the flow path to the patient this flow path must be primed to remove any air bubbles. To allow the air to escape the priming typically is done by removal of the luer cap and visually observing the fluid flow through the flow path until a small amount is emitted from a luer connection at the end of the flow path. Then the luer connection is attached to a catheter which has been inserted into the patient.
This process, however, is often time consuming and requires the constant attention of medical personnel to determine whether priming has been accomplished by watching the end of the tubing line to see if the fluid is dripping at the end of the line. The slower the flow rate of fluid through the flow line the longer the medical personnel will need to observe the filling of the flow line.
Because the fluid may be costly or may be harmful if exposed to persons, it is important to know as soon as possible once an intravenous line has been fully primed and is ready to have its contents delivered into a patient without exposing the environment to the fluid. It is also important that the priming can occur without the necessity of constant monitoring.
U.S. Pat. No. 5,318,520 to Nakao describes a device for use in intravenous feeding, having a reservoir of an intravenous fluid and an intravenous tube connected at one end to a reservoir. The tube is provided on an inner surface with a layer of a water-soluble biocompatible material that is visible through a transparent wall of the tube. During use, an intravenous fluid is flushed through the tube until the water-soluble biocompatible layer dissolves and is no longer visible. This is accomplished using an indicator layer with a predetermined thickness and density, whereby the layer dissolves upon flushing of a predetermined amount of fluid through the tube. Effectively, this provides an indication to a nurse or doctor that an intravenous line may or may not have been sufficiently flushed with intravenous fluid to remove all of the residual air from the line. Nakao, U.S. Pat. No. 5,318,520, also describes an alternate embodiment in which a separate connector piece is provided on a free end of the intravenous tube, with the inner surface of only the separate connector piece being provided with an inner surface having the layer of water-soluble biocompatible material that dissolves upon flushing of the tube and connector member with intravenous fluid. In each embodiment, after priming, any residual biocompatible material on the interior of the tube or connector gets flushed into the patient with the intravenous fluid.
Accordingly, it is realized that there are still unmet needs for a priming indicator in infusion systems that provides an indication to medical personnel when priming of the flow path is complete, and without adding any leachables or potential contaminants to intravenous fluid to be delivered to a patient.